/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.optimize;

import proguard.classfile.*;
import proguard.classfile.editor.ClassReferenceFixer;
import proguard.classfile.util.*;
import proguard.classfile.visitor.MemberVisitor;
import proguard.evaluation.value.Value;
import proguard.optimize.evaluation.StoringInvocationUnit;

/**
 * This MemberVisitor specializes parameters in the descriptors of the methods that it visits.
 *
 * @see StoringInvocationUnit
 * @see ClassReferenceFixer
 * @author Eric Lafortune
 */
public class MemberDescriptorSpecializer extends SimplifiedVisitor implements MemberVisitor {
    private static final boolean DEBUG = false;

    private final MemberVisitor extraParameterMemberVisitor;

    /**
     * Creates a new MethodDescriptorShrinker.
     */
    public MemberDescriptorSpecializer() {
        this(null);
    }

    /**
     * Creates a new MethodDescriptorShrinker with an extra visitor.
     * 
     * @param extraParameterMemberVisitor an optional extra visitor for all class members whose parameters have been
     *        specialized.
     */
    public MemberDescriptorSpecializer(MemberVisitor extraParameterMemberVisitor) {
        this.extraParameterMemberVisitor = extraParameterMemberVisitor;
    }

    // Implementations for MemberVisitor.

    public void visitProgramField(ProgramClass programClass, ProgramField programField) {
        Value parameterValue = StoringInvocationUnit.getFieldValue(programField);
        if (parameterValue.computationalType() == Value.TYPE_REFERENCE) {
            Clazz referencedClass = parameterValue.referenceValue().getReferencedClass();
            if (programField.referencedClass != referencedClass) {
                if (DEBUG) {
                    System.out.println("MemberDescriptorSpecializer: " + programClass.getName() + "."
                        + programField.getName(programClass) + " " + programField.getDescriptor(programClass));
                    System.out
                        .println("  " + programField.referencedClass.getName() + " -> " + referencedClass.getName());
                }

                programField.referencedClass = referencedClass;

                // Visit the field, if required.
                if (extraParameterMemberVisitor != null) {
                    extraParameterMemberVisitor.visitProgramField(programClass, programField);
                }
            }
        }
    }

    public void visitProgramMethod(ProgramClass programClass, ProgramMethod programMethod) {
        // All parameters of non-static methods are shifted by one in the local
        // variable frame.
        int firstParameterIndex = (programMethod.getAccessFlags() & ClassConstants.ACC_STATIC) != 0 ? 0 : 1;

        int parameterCount = ClassUtil.internalMethodParameterCount(programMethod.getDescriptor(programClass));

        int classIndex = 0;

        // Go over the parameters.
        for (int parameterIndex = firstParameterIndex; parameterIndex < parameterCount; parameterIndex++) {
            Value parameterValue = StoringInvocationUnit.getMethodParameterValue(programMethod, parameterIndex);
            if (parameterValue.computationalType() == Value.TYPE_REFERENCE) {
                Clazz referencedClass = parameterValue.referenceValue().getReferencedClass();
                if (programMethod.referencedClasses[classIndex] != referencedClass) {
                    if (DEBUG) {
                        System.out.println("MemberDescriptorSpecializer: " + programClass.getName() + "."
                            + programMethod.getName(programClass) + programMethod.getDescriptor(programClass));
                        System.out.println("  " + programMethod.referencedClasses[classIndex].getName() + " -> "
                            + referencedClass.getName());
                    }

                    programMethod.referencedClasses[classIndex] = referencedClass;

                    // Visit the method, if required.
                    if (extraParameterMemberVisitor != null) {
                        extraParameterMemberVisitor.visitProgramMethod(programClass, programMethod);
                    }
                }

                classIndex++;
            }
        }
    }
}
